Automatic brake adjusters for all types of brakes and especially for disc brakes are known. Usually the brake adjuster operates by a moving portion of the brake engaging a fixed portion of the brake apparatus to prevent excessive return movement of the brake applying member.
Disc brakes present a special problem because the clearance between the brake pad or brake shoe and the disc when the brake is not applied is very small. For that reason, the adjustment must be very small and automatic adjustment must occur in a very short movement of the brake apparatus.